My 1.16.5 mod isn't working and the game crashes

So basically, I just created my own mod for the first time and wanted to see if it worked. However every time I try to test the mod and hit single player, it ends up crashing. I tested this on the actual minecraft launcher, and the same thing happened. Except this time on the launcher there was a message that read "The game crashed whilst mouseclicked event handler
Error: java.lang.IllegalStateException: Missing: ResourceKey[minecraft:worldgen/biome / roberts_cool_mod:shut] Exit Code: -1." If anyone could help me troubleshoot this problem, that'd be great.